Asphalted roofing-board is a common roofing material. The expansion of such a material due to moisture pick-up amounts to about 3-4%. There has been a long-felt need for a board-or sheet-shaped material for the above or similar purposes, which material has a considerably lower expansion, i.e. a higher dimensional stability.
Paper materials with a high amount of glass or mineral fibres are previously known through, e.g. GB-A-1,277,858 and DK-B-136-542. A problem when handling glass and other mineral fibres and mixing them into wet masses, is to provide a wetting of the fibres, so that the fibers, by simple means, can be kept separated in the mass.
In US-A-2,787,542, there is described a device for manufacturing a paper-like material with a high amount of glass fibres. The fibres are delivered into a hood, where they are hit by water sprays so that they are wetted. Water and fibres are then carried downwardly into a pulp vat of a paper-making machine. The fibres in this case have to be easily wettable, and the device would not work for fibres which e.g., contain a binding agent, like e.g., phenolic resin.